The flexible tubular pipes according to the invention, that are well known to the person skilled in the art, are used primarily for extracting oil offshore and are for example defined by the standard API RP 17J or 17B API of the American Petroleum Institute (API). Generally, the structure consists of a superposition of several layers, which include: a metal carcass, an inner polymeric sealing sheath or “pressure sheath”, armour layers wound on the outside around the pressure sheath in order to be able to withstand the compressive forces exerted by the flow of petroleum fluid and the longitudinal tensile stress. At least one first armour layer comprises of at least one armour wire wound with short pitched winding over the impervious sheath and forming contiguous turns or a “pressure vault”. And at least one second armour layer comprising of armour wires wound with long pitched winding, is arranged around the pressure vault. Usually, an outer polymeric sheath is extruded over the at least one second armour layer.
A technology known from the state of the art, in particular from the document WO 99/19656, involves executing the assembling of a metal carcass for a flexible tubular pipe with an additional element in a manner so as to facilitate the anchoring thereof within a connecting end fitting.
The additional element is a lock ring positioned at the end of the metal carcass and intended to cooperate with a groove provided in the connecting end fitting by means of a screwing action along a thread defined by the winding of the profiled metal strips.
The lock ring is fixed on to the carcass by means of welding or quite simply by making use of a screw, in order to hold the assembly together securely. However, such an assembly presents the disadvantage of not having the ability to easily adapt to any type of carcass: the manufacture of the lock ring being dependent on the dimension of the outer diameter of the carcass around which it is intended to be mounted. On the other hand, the assembly may require the use of a weld seam to hold the ring and carcass together in an integrally secure manner, which represents an extra operation and thus does not allow for the possibility of having the assembly assembled in an irreversible manner.
Furthermore, in the document WO 01/50056, a description is given of the assembling of at least two sections of metal carcass of flexible tubular pipe connected to one another. Each section of the carcass, formed by the winding of a plurality of profiled strips describe a screw thread.
In advance, two holes are machined into each of the sections. The first section is positioned coaxially with respect to the subsequent section and they are then fixed to each other by means of an operation of screwing the two profiled strips together until the two holes machined into each of them coincide. They are then held together in an integrally secured manner by means of screw-nut systems. One of the disadvantages of this type of assembly is that it is necessary for each section of carcass to be machined in order to connect them to each other. Such a machining process may eventually lead to the phenomena of localised corrosion and/or to problems related to mechanical strength and resistance to tensile stresses.